Kalman Filtering Based Speech Enhancement Using a Codebook Based Approach

1. A hearing device for enhancing speech intelligibility, the hearing device comprising: an input transducer for providing an input signal comprising a speech signal and a noise signal; a processing unit; an acoustic output transducer coupled to the processing unit; wherein the processing unit is configured to determine one or more parameters based on a codebook based approach (CBA) processing; wherein the processing unit is configured to perform Kalman filtering based on the input signal and the one or more parameters to provide an output signal having an enhanced speech intelligibility; and wherein the acoustic output transducer is configured to provide an audio output signal for hearing by a user of the hearing device based on the output signal with enhanced speech intelligibility.

2. The hearing device according to claim 1 , wherein the input signal is divided into one or more frames, the one or more frames comprising primary frames representing speech signals, secondary frames representing noise signals, tertiary frames representing silence, or any combination of the foregoing.

3. The hearing device according to claim 1 , wherein the one or more parameters comprise one or a combination of: a first parameter being a state evolution matrix C(n) comprising of speech Linear Prediction Coefficients (LPC) and noise Linear Prediction Coefficients (LPC), a second parameter being a variance of a speech excitation signal σ u 2 (n), and a third parameter being a variance of a noise excitation signal σ v 2 (n).

4. The hearing device according to claim 1 , wherein the one or more parameters are assumed to be constant over frames of 25 milliseconds.

5. The hearing device according to claim 1 , wherein the processing unit is configured to determine the one or more parameters based on a priori information about speech spectral shapes and/or noise spectral shapes stored in a codebook in a form of Linear Prediction Coefficients (LPC).

6. The hearing device according to claim 1 , wherein the codebook based approach (CBA) processing involves a generic speech codebook or a speaker specific trained codebook.

7. The hearing device according to claim 1 , wherein the code book based approach (CBA) processing involves a speaker specific trained codebook, and wherein the speaker specific trained codebook comprises data based on recording speech of multiple persons.

8. The hearing device according to claim 1 , wherein the processing unit is configured to perform the Kalman filtering using a fixed lag Kalman smoother that is configured to provide a minimum mean-square estimator (MMSE) of the speech signal.

9. The hearing device according to claim 1 , wherein the processing unit is configured to perform the Kalman filtering based on the input signal by computing an a priori estimate and an a posteriori estimate of a state vector, and an error covariance matrix of the input signal.

10. The hearing device according to claim 1 , wherein the processing unit is configured to perform a weighted summation of predictor parameters of the speech signal in a line spectral frequency (LSF) domain.

11. The hearing device according to claim 1 , wherein the hearing device is a first hearing device configured to communicate with a second hearing device in a binaural hearing device system configured to be worn by the user.

12. The hearing device according to claim 11 , wherein the input transducer comprises a first input transducer, the input signal comprises a left ear input signal, and wherein the first hearing device comprises the first input transducer for providing the left ear input signal; wherein the second hearing device comprises a second input transducer for providing a right ear input signal comprising a right ear speech signal and a right ear noise signal; wherein the processing unit comprises a first processing unit, the one or more parameters of the input signal comprises one or more left parameters of the left ear input signal, and wherein the first hearing device comprises the first processing unit configured for determining the one or more left parameters of the left ear input signal based on the codebook based approach (CBA) processing; and wherein the second hearing device comprises a second processing unit configured for determining one or more right parameters of the right ear input signal.

13. The hearing device according to claim 1 , wherein the codebook based approach (CBA) processing involves a codebook corresponding to a category of human speaker.

14. The hearing device according to claim 13 , wherein category of human speaker comprises a female category, a male category, a child category, or a combination of the foregoing.

15. The hearing device according to claim 13 , wherein the category of human speaker comprises a known-person category.

16. The hearing device according to claim 1 , wherein the codebook based approach (CBA) processing involves a codebook corresponding to a category of speech-source.

17. The hearing device according to claim 1 , wherein the hearing device is configured for worn by the user.

18. A hearing device for enhancing speech intelligibility, the hearing device comprising: an input transducer for providing an input signal comprising a speech signal and a noise signal; a processing unit; an acoustic output transducer coupled to the processing unit; wherein the processing unit is configured to determine one or more parameters based on a codebook based approach (CBA) processing; wherein the processing unit is configured to perform Kalman filtering based on the input signal and the one or more parameters to provide an output signal having an enhanced speech intelligibility; wherein the acoustic output transducer is configured to provide an audio output signal for hearing by a user of the hearing device based on the output signal with enhanced speech intelligibility; and wherein the one or more parameters comprise one or more predictor parameters, and wherein the Kalman filtering is performed based on the one or more predictor parameters.

19. A hearing device for enhancing speech intelligibility, the hearing device comprising: an input transducer for providing an input signal comprising a speech signal and a noise signal; a processing unit; an acoustic output transducer coupled to the processing unit; wherein the processing unit is configured to determine one or more parameters based on a codebook based approach (CBA) processing; wherein the processing unit is configured to perform Kalman filtering based on the input signal and the one or more parameters to provide an output signal having an enhanced speech intelligibility; wherein the acoustic output transducer is configured to provide an audio output signal for hearing by a user of the hearing device based on the output signal with enhanced speech intelligibility; and wherein the processing unit is configured to automatically select a codebook for the codebook based approach (CBA) processing from a plurality of available codebooks, and wherein the processing unit is configured to automatically select the codebook based on a spectra of the input signal and/or based on a measurement of objective intelligibility for each of the available codebooks.

20. A method for enhancing speech intelligibility in a hearing device, the method comprising: providing an input signal comprising a speech signal and a noise signal; determining, using a processing unit, one or more parameters of the input signal based on a codebook based approach (CBA) processing; performing, using the processing unit, Kalman filtering based on the input signal and the one or more parameters to generate an output signal that has an enhanced speech intelligibility; and providing an audio output signal by an acoustic output transducer for hearing by a user of the hearing device based on the output signal.

21. The method according to claim 20 , wherein the hearing device is configured for worn by the user.